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Full text of "Text Book Of Mechanical Engineering"

558

Friction of Turning Pairs.

Friction of -a Collar Bearing.  This was examined
under the same auspices. Here the friction was nearer the
4 solid ' condition, the lubrication being less perfect. The
pressure/ varied from 15 to 90 Ibs., and v from 5 to 15 ft. per
sec. The coefficient was '036 for ordinary loads, the usual
formula being applicable. (See p. 871.)

Work Lost in Journal or Collar Friction.  R being
outside or mean radius respectively,

Work lost in foot pounds per m. = FnxV = ^Px2

TT_.

H> P. lost = -

33000
Work Lost in Pivot Friction.  Following the method

of Fig. 371, let r be the pivot radius in Fig. 572.    Assuming the

pressure to be equally distributed,

p                                               p

- = pressure per sq. in,,  and -5- = force of friction per sq. in.

irf^                                                         Trf^

Total friction on any ring = unit friction x area of ring

itP                      2LlP

.'. Total friction on outer ring == *--s x 2wr x ^ = "^ x f

and   Total friction on ring r%   x -* x f